performance issue win10 stations to cifs share

Hello, ontap version:8.1.4 7-Mode netapp model:FAS2240-2 when clients from remote offices use the Netapp CIFS share (via VPN or WAN) they experience slow browsing between folders (entering folders). that only occurs from win10 stations, win7 station works fine (from remote and local offices). copy files form CIFS share works well from both types of stations. Any advice greatly received.